Microbiology Exam 3 - Cellular Processes, Antimicrobial Chemotherapy
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228 Terms
What are the two main approaches to cellular regulation?
Regulation of gene expression and alteration of enzyme/protein activity.
What are the three levels where gene expression is regulated?
Transcription (initiation/elongation), translation, and posttranslation.
What is the role of "Constitutive Genes"?
Housekeeping genes that are expressed continuously by the cell.
Genes that code for enzymes only needed under certain conditions
Inducible Genes
What is the function of "B-galactosidase"?
It hydrolyzes lactose into galactose and glucose.
In an inducible system, what is the role of an "Inducer"?
A small effector molecule that stimulates gene expression.
Where do regulatory proteins typically bind on DNA?
The operator.
Regulatory proteins that inhibit transcription (negative control)
Repressors
Regulatory proteins that promote transcription (positive control)
Activators
Small effector molecules that bind to repressors to make them active
Corepressors
Small effector molecules that bind to repressors to make them inactive
Inducers
Define "Operon"
A promoter and operator or effector genes together with the structural genes they control.
What is the "lac operon"?
A negative-inducible system controlled by the lac repressor and the presence of lactose.
What happens to the lac operon when lactose is absent?
The lac repressor binds to the operator, inhibiting transcription.
What is "allolactose"?
The inducer for the lac operon (converted from lactose).
What protein provides positive control for the lac operon?
Catabolite Activator Protein (CAP).
What is "Catabolite Repression"?
The preferential use of one carbon source (like glucose) over others.
What signal molecule indicates low glucose levels in the cell?
cAMP (cyclic AMP).
The regulation of transcription by the leader sequence and "stem-loop" structures
Attenuation
Which operon is a famous example of attenuation?
The tryptophan (trp) operon.
What are "Riboswitches"?
Regions in the 5' untranslated leader of mRNA that bind metabolites to regulate transcription or translation.
Where are riboswitches that function by transcriptional termination primarily found?
Gram-positive bacteria.
Where are riboswitches that function by translational repression primarily found?
Gram-negative bacteria.
Small RNA molecules that do not function as mRNA, tRNA, or rRNA
sRNAs (small RNAs) or noncoding RNAs.
How do antisense sRNAs typically function?
By base-pairing to complementary mRNA to inhibit or promote translation.
A regulatory system that uses a sensor kinase and a response regulator
Two-Component Signal Transduction System.
The enzyme that spans the plasma membrane and detects environmental signals
Sensor kinase.
The protein that is phosphorylated by the sensor kinase to act as a transcription factor
Response regulator.
Cell-to-cell communication based on population density
Quorum Sensing
What is the most common autoinducer in Gram-negative bacteria?
Acyl homoserine lactone (AHL).
What is the purpose of the Stringent Response?
To downregulate synthesis of tRNA and rRNA when amino acids are low.
What are "Alarmones"?
Signaling molecules like ppGpp produced during the stringent response.
Proteins that assist in folding or refolding partially denatured proteins
Chaperones (Heat Shock Proteins).
What is a "Global Regulator"?
A protein that affects many genes and pathways simultaneously.
What are "Regulons"?
A collection of genes or operons controlled by a common global regulatory protein.
The three stages of the CRISPR/Cas system
1. Adaptation, 2. Expression, 3. Interference.
What occurs during the CRISPR "Adaptation" stage?
Pieces of a viral genome are added to the CRISPR array if the cell survives.
What are "crRNAs"?
Mature CRISPR RNAs that associate with Cas proteins to destroy viral DNA.
An innate immune system that uses enzymes to cut viral DNA at specific sequences
Restriction-Modification System.
How do cells protect their own DNA from restriction enzymes?
By adding methyl groups to their DNA (Methylation).
The movement of a mobile genetic element from one DNA location to another
Transposition.
Short DNA segments that only contain the gene for the enzyme transposase
Insertion Sequences (IS).
What is a "Composite Transposon"?
A transposon containing extra genes (like antibiotic resistance) flanked by IS elements.
The complete set of genetic information in an organism
Genome.
The study of the molecular organization of genomes
Genomics.
What is "Functional Genomics"?
The study of how genes work to produce phenotypes.
The entire collection of proteins that an organism can produce
Proteome.
What is "Metagenomics"?
The study of genetic material recovered directly from environmental samples.
What are the two main approaches to cellular regulation?
Regulation of gene expression and alteration of enzyme/protein activity.
What are the three levels where gene expression is regulated?
Transcription (initiation/elongation), translation, and posttranslation.
What is the role of "Constitutive Genes"?
Housekeeping genes that are expressed continuously by the cell.
Genes that code for enzymes only needed under certain conditions
Inducible Genes
What is the function of "B-galactosidase"?
It hydrolyzes lactose into galactose and glucose.
In an inducible system, what is the role of an "Inducer"?
A small effector molecule that stimulates gene expression.
Where do regulatory proteins typically bind on DNA?
The operator.
Regulatory proteins that inhibit transcription (negative control)
Repressors
Regulatory proteins that promote transcription (positive control)
Activators
Small effector molecules that bind to repressors to make them active
Corepressors
Small effector molecules that bind to repressors to make them inactive
Inducers
Define "Operon"
A promoter and operator or effector genes together with the structural genes they control.
What is the "lac operon"?
A negative-inducible system controlled by the lac repressor and the presence of lactose.
What happens to the lac operon when lactose is absent?
The lac repressor binds to the operator, inhibiting transcription.
What is "allolactose"?
The inducer for the lac operon (converted from lactose).
What protein provides positive control for the lac operon?
Catabolite Activator Protein (CAP).
What is "Catabolite Repression"?
The preferential use of one carbon source (like glucose) over others.
What signal molecule indicates low glucose levels in the cell?
cAMP (cyclic AMP).
The regulation of transcription by the leader sequence and "stem-loop" structures
Attenuation
Which operon is a famous example of attenuation?
The tryptophan (trp) operon.
What are "Riboswitches"?
Regions in the 5' untranslated leader of mRNA that bind metabolites to regulate transcription or translation.
Where are riboswitches that function by transcriptional termination primarily found?
Gram-positive bacteria.
Where are riboswitches that function by translational repression primarily found?
Gram-negative bacteria.
Small RNA molecules that do not function as mRNA, tRNA, or rRNA
sRNAs (small RNAs) or noncoding RNAs.
How do antisense sRNAs typically function?
By base-pairing to complementary mRNA to inhibit or promote translation.
A regulatory system that uses a sensor kinase and a response regulator
Two-Component Signal Transduction System.
The enzyme that spans the plasma membrane and detects environmental signals
Sensor kinase.
The protein that is phosphorylated by the sensor kinase to act as a transcription factor
Response regulator.
Cell-to-cell communication based on population density
Quorum Sensing
What is the most common autoinducer in Gram-negative bacteria?
Acyl homoserine lactone (AHL).
What is the purpose of the Stringent Response?
To downregulate synthesis of tRNA and rRNA when amino acids are low.
What are "Alarmones"?
Signaling molecules like ppGpp produced during the stringent response.
Proteins that assist in folding or refolding partially denatured proteins
Chaperones (Heat Shock Proteins).
What is a "Global Regulator"?
A protein that affects many genes and pathways simultaneously.
What are "Regulons"?
A collection of genes or operons controlled by a common global regulatory protein.
The three stages of the CRISPR/Cas system
1. Adaptation, 2. Expression, 3. Interference.
What occurs during the CRISPR "Adaptation" stage?
Pieces of a viral genome are added to the CRISPR array if the cell survives.
What are "crRNAs"?
Mature CRISPR RNAs that associate with Cas proteins to destroy viral DNA.
An innate immune system that uses enzymes to cut viral DNA at specific sequences
Restriction-Modification System.
How do cells protect their own DNA from restriction enzymes?
By adding methyl groups to their DNA (Methylation).
The movement of a mobile genetic element from one DNA location to another
Transposition.
Short DNA segments that only contain the gene for the enzyme transposase
Insertion Sequences (IS).
What is a "Composite Transposon"?
A transposon containing extra genes (like antibiotic resistance) flanked by IS elements.
The complete set of genetic information in an organism
Genome.
The study of the molecular organization of genomes
Genomics.
What is "Functional Genomics"?
The study of how genes work to produce phenotypes.
The entire collection of proteins that an organism can produce
Proteome.
What is "Metagenomics"?
The study of genetic material recovered directly from environmental samples.
What are the two main approaches to cellular regulation?
Regulation of gene expression and alteration of enzyme/protein activity.
Define "Constitutive Genes"
Housekeeping genes that are expressed continuously because they are always needed.
Genes that code for enzymes only needed under certain conditions
Inducible Genes
What is the function of β-galactosidase?
It catalyzes the hydrolysis of lactose into galactose and glucose.
